My battery us good on my 2000 Chevy Blazer but it wont start all of a sudden.

Maybe a bad starter?

I WOULD TAKE SPARK PLUGS OUT OF MOTOR MAKE SHURE NO WATER IN CYLINDERS IF THERE IS REDO INTAKE MANIFOLD

sounds like time to change Ignition switch in steering column

IF THE MOTOR WILL START WHEN YOU JUMP START, THE BATTERY IN THE BLAZER MUST BE LOW. USE A D.C. VOLTMETER, THE VOLTAGE AT THE BATTERY WITHOUT JUMPER CABLES, SHOULD NOT DROP BELOW 9 VOLTS WHEN THE STARTER IS TURNING. THERE IS A CRANK FUSE IN THE INTERIOR FUSEBOX. & A STARTER RELAY UNDER THE HOOD. BUT IF THE STARTER IS TURNING, THOSE ITEMS ARE WORKING. THEY ARE ONLY TO MAKE THE STARTER TURN. GOOD LUCK, DRVOLT.

If it won't restart now by jumping with another battery, unfortunately sounds like the starter has locked up...sometimes but not always, you can use a hammer to tap the starter then try again...as this works...you need to replace the starter so you won't be stranded:)

Try to get a jump you may have power but not enough to turn it over. If that don't work you will then need to replace starter. I had the ame problem last week with my 1995 blazer and i put a new starter on it and she fie rd right over. God bless and good luck to you and your vehicle.

Have replaced starter, alternator , ignition wiring, neutral safety starter switch, still happens ??????? Do you know how to do automotive electrical testing ? Not guessing an replacing parts . Not starting ??? How ? when you turn the key to start does the starter motor engage an spin the engine ? Or when you turn the key to start nothing happens ? A no crank no start or a cranks no start . Plus you shoud learn how the system works before trying to diagnose .

get a load test done on you battery and alter nator and check your starter for corrision check battery connections before you jump start it and when hooking up cables to your truck let it charge for a few minutes before you crank it if alternator is fried it will only run on juice of battery then will die.the clicking sound is your starter trying to engage but not enough cranking amps left in battery if you can get it going or take the battery out and take to a good auto shop and get them to load test it no point replacing a good battery just to find out it is alternator or starter
I personaaly think it may be alternator but suggest you test if battery is good starter as well ! more thing check that battery terminals are clean and tight

cracked cylinder head or blown gasket

CHECK THE CRANK SENSOR